An input apparatus including an electronic pen and a terminal having a foldable display unit is provided. An electronic pen generates an ultrasonic signal and an infrared signal. A terminal detects the ultrasonic signal and the infrared signal and calculates coordinate information of the electronic pen based on the received ultrasonic signal and the infrared signal. The terminal determines coordinate information of the electronic pen with respect to the foldable display unit by measuring a folding angle of the foldable display unit.